JP2003269124A - Variable valve device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that it is difficult to start an engine well because of high friction of the engine resulting from high viscosity of an engine oil at an extremely low temperature further lower than the temperature of the engine when cooled. <P>SOLUTION: This variable valve device comprises an operating angle changing mechanism 10 for changing an inlet operating angle of an inlet valve, a phase changing mechanism 20 for changing an inlet center phase, and means 36 for estimating the temperature of the engine. In a region of extremely low loading including idling, the inlet operating angle at the extremely low temperature is at least about 180° CA larger than the inlet operating angle with the engine cooled and the inlet center phase is about 90° ATDC. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an operating angle changing mechanism capable of changing an operating angle (intake operating angle) of an intake valve and a phase changing capable of changing a central phase of the operating angle of the intake valve (intake central phase). And a variable valve operating device for an internal combustion engine having both the mechanism and the mechanism.

[0002]

2. Description of the Related Art Conventionally, various variable valve operating devices for changing the opening / closing characteristics (valve lift characteristics) of intake valves and exhaust valves have been proposed in order to improve the output and fuel consumption of internal combustion engines and reduce exhaust emissions. Has been done. For example, JP 2000-
Japanese Patent No. 18056 discloses a valve lift amount changing mechanism capable of changing a valve lift amount and an operating angle of an intake valve in two steps.
A variable valve operating device is disclosed that uses a valve timing changing mechanism that can continuously change the central phase of the operating angle of an intake valve.

[0003]

In order to improve fuel efficiency and reduce exhaust emissions in such a variable valve operating device, it is preferable to reduce the intake working angle in an extremely low load range including idle. However, at an extremely low temperature such as when the engine temperature drops below -20 ° C in a cold region, the friction of the engine becomes extremely high mainly due to the increase in the viscosity of the engine oil. Therefore, in the extremely low load range above,
In addition, if the intake working angle is made small as described above under the condition of extremely low temperature, it is not possible to obtain sufficient engine torque to start the engine against the above-mentioned engine friction, resulting in deterioration of engine startability. May invite. The present invention has been made in view of such problems.

[0004]

A variable valve operating system for an internal combustion engine according to the present invention is capable of changing an intake operating angle of an intake valve, and an intake central phase of the intake operating angle. It has a phase changing mechanism and an engine temperature estimating means for estimating the engine temperature. Then, in an extremely low load range including at least the idle, the intake working angle when the engine temperature is extremely low, which is lower than when the engine is cold, is made larger than at least the intake working angle when the engine is cold. Typically, the intake working angle is set to about 18 at the extremely low temperature in the extremely low load range.
0 ° CA (crank angle), the intake center phase is approximately 90
Set to ATDC (angle after top dead center).

Even during acceleration from the same load range, the change mechanism that is driven preferentially (previously) is switched based on the engine speed or the engine temperature, so that the torque during acceleration is increased. It is possible to prevent the depression and improve the engine operation performance.

[0006]

According to the present invention, the intake working angle is appropriately adjusted according to the engine temperature in the extremely low load range. That is,
Good engine startability is ensured by making the intake working angle relatively large at extremely low temperatures, while the intake working angle is made relatively small at least in conditions other than extremely cold including cold time. It is possible to improve exhaust emission and fuel efficiency.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 shows a variable valve operating device according to an embodiment of the present invention. A pair of intake valves 2 is provided in each cylinder, and a hollow intake drive shaft 3 is provided above the intake valves 2.
Extend in the cylinder row direction. A swing cam 4 that abuts on a valve lifter 2a of the intake valve 2 to open / close the intake valve 2 is fitted onto the intake drive shaft 3 so as to be relatively rotatable.

Between the intake drive shaft 3 and the oscillating cam 4, an electric operating angle changing mechanism 10 for continuously changing the operating angle of the intake valve 2 and the valve lift amount is provided. ing. An electric phase at one end of the intake drive shaft 3 for continuously changing the intake center phase, which is the center phase of the intake working angle, by changing the phase of the intake drive shaft 3 with respect to a crankshaft (not shown). A changing mechanism 20 is provided.

As shown in FIGS. 1 and 2, the operating angle changing mechanism 10 has a circular drive cam 11 which is eccentrically and fixedly provided on the intake drive shaft 3 and is externally fitted to the drive cam 11 so as to be relatively rotatable. Ring-shaped link 12, a control shaft 13 extending in the cylinder row direction substantially parallel to the intake drive shaft 3, and the control shaft 1
A circular control cam 14 that is eccentrically provided and fixedly provided
And a rocker arm 15 that is fitted to the control cam 14 so as to be relatively rotatable and has one end connected to the tip of the ring-shaped link 12, and a rod shape that is connected to the other end of the rocker arm 15 and the swing cam 4. And a link 16. The control shaft 13 is rotationally driven within a predetermined control range by an electric actuator 17 via a gear train 18.

With the above structure, when the intake drive shaft 3 rotates in conjunction with the crankshaft, the ring-shaped link 12 moves substantially in translation through the drive cam 11, and the rocker arm 15 moves around the axis of the control cam 14. The rocking cam 4 rocks and the rocking cam 4 rocks via the rod-shaped link 16 to open and close the intake valve 2. Further, by changing the rotation angle of the control shaft 13, the axial center position of the control cam 14, which is the rocking center of the rocker arm 15, changes, and the attitude of the rocking cam 4 changes. As a result, the intake working angle and the valve lift amount continuously change while the intake center phase remains substantially constant.

In such an operating angle changing mechanism 10, since the connecting portions of the respective members such as the bearing portion of the drive cam 11 and the bearing portion of the control cam 14 are in surface contact, lubrication is easy and durability, It has excellent reliability. Further, since the swing cam 4 that drives the intake valve 2 is disposed coaxially with the intake drive shaft 3, for example, the swing cam is supported by a support shaft different from the intake drive shaft 3. In comparison, the control accuracy is excellent and the device itself is compact,
It has excellent institutional mountability. Especially for direct acting valve trains,
It can be applied without major layout changes. Furthermore, since a biasing means such as a return spring is not required, friction in the valve train can be suppressed low.

E as an engine control unit
The CU 30 operates the engine such as the angle of the intake drive shaft 3 and the control shaft 13 detected by the angle detection sensors 31 and 32, as well as the crank angle, engine speed, load, engine temperature, etc. detected or estimated by various sensors. Based on the conditions, general engine control such as fuel injection control and ignition timing control is performed, and the intake working angle and intake center phase of the intake valve 2 are changed and controlled as described later. Further, the ECU 30 estimates the engine temperature (oil water temperature) based on at least one of the cooling water temperature detected by the well-known water temperature sensor 34 and the oil temperature detected by the well-known oil temperature sensor 35. Means 36 are included, and it is possible to accurately determine, based on the engine temperature, whether the engine is warmed up, which will be described later, that is, whether the engine is at a very low temperature, cold, or warmed up.

FIG. 3 shows an electric phase changing mechanism 20. The phase changing mechanism 20 is fixed to a cam sprocket 25 that rotates in synchronization with the crankshaft, and is fixed to one end of the intake drive shaft 3 by a first rotating body 21 that rotates integrally with the cam sprocket 25 and a bolt 22a. The second rotating body 22 that rotates integrally with the intake drive shaft 3 and the first rotating body 21 by the helical spline 26.
And a cylindrical intermediate gear 23 that meshes with the inner peripheral surface of the first rotating body 22 and the outer peripheral surface of the second rotating body 22. A drum 27 is connected to the intermediate gear 23 via a triple thread 28, and a torsion spring 29 is interposed between the drum 27 and the intermediate gear 23. The intermediate gear 23 is biased in a retard angle direction (leftward in FIG. 3) by a torsion spring 29. When a voltage is applied to the electromagnetic retarder 24 to generate a magnetic force, the intermediate gear 23 passes through the drum 27 and the three-thread screw 28. It is moved in the advance direction (to the right in FIG. 3). Depending on the axial position of the intermediate gear 23, the relative phase of the rotating bodies 21, 22 changes, and the phase of the intake drive shaft 3 with respect to the crankshaft changes. The electromagnetic retarder 24 is the ECU described above.
Drive control is performed according to the engine operating state by a control signal from 30.

FIG. 4 is a flow chart showing the flow of setting / controlling the intake working angle and the intake center phase at the time of starting the engine and in the extremely low load region, which is the main part of this embodiment. This routine is executed by the ECU 30. . S (step) 1
In step S3, if it is determined that the engine is being started, or if it is determined in S2 that the engine is in the extremely low load range including idle, the process proceeds to step S3 and the engine temperature estimation means 3 is used.
The engine temperature estimated by 6 is read. The memory of the ECU 30 stores in advance tables and maps corresponding to FIG. 5 (a) and FIG. 6 (b) (or (c)) described later, and in S4, these tables and maps are stored based on the engine temperature. The target values of the intake working angle and the intake center phase are calculated by referring to the table and the map. In S5, control signals corresponding to these target values are output to the electric actuator 17 of the operating angle changing mechanism 10 and the electromagnetic retarder 24 of the phase changing mechanism 20. The intake working angle and the intake center phase are adjusted independently of each other according to these control signals.
When the idle determination in S2 is denied, the routine proceeds to S6, and another routine (not shown) sets and controls the intake working angle and the intake center phase according to the engine speed and the engine load.

5 to 7 show the intake valve lift characteristics with respect to the engine temperature in the extremely low load range including the engine startup or idling, and FIG. 5 (a) shows the characteristics of the intake working angle, and FIG. (B) shows the characteristics of the intake center phase. In the present specification, the term "during cold operation" is, as is well known, a room temperature state before warming up, and is typically when the engine temperature is about 20 ° C. The "extremely low temperature" is a time when the engine temperature is lower than that during normal cooling in a cold region or the like, typically -20 ° C or lower.

At an extremely low temperature, the viscosity of the engine oil as the lubricating oil is high and the friction of the engine becomes large as compared with that at the time of cooling, so that it is large enough to maintain at least the idle speed against this friction. It is necessary to generate engine torque. Therefore, in this embodiment,
At such an extremely low temperature, the intake working angle 40a is about 180 °.
CA and the intake center phase 40b are set to about 90 ° ATDC. That is, the IVO of the intake valve lift characteristic 40 is near TDC and the IVC is near BDC. As a result, the intake valve opens without excess or deficiency corresponding to the intake stroke, that is, there is almost no valve overlap or minus overlap, and it is possible to maintain sufficient idle speed against the above friction. Torque can be generated. Therefore, it is possible to ensure good engine startability and perform a quick warm-up operation even in the extremely low temperature state.

When the engine is cold, the intake working angle 42a is set to a minimum working angle of about 80 ° to 100 ° CA, preferably 90 ° C.
A, and the intake center phase 42b is 180 degrees which is the most retarded angle phase.
By setting ATDC, that is, in the vicinity of BDC, the IVO of the intake valve lift characteristic 42 is significantly retarded compared to TDC, and the retard limit of the ignition timing is expanded to accelerate the rise in exhaust temperature and raise the catalyst. Shorten the warming time to improve exhaust emission. Further, by minimizing the intake working angle, the friction of the valve operating system is suppressed to the minimum, and the gas flow is strengthened to promote atomization of the fuel.

After warming up, the intake operating angle 44a is kept at the same minimum operating angle as during cold cooling, and the intake center phase 44b is advanced more than during cold cooling to reduce pump loss compared to during cold cooling and improve fuel economy. Improve.

During the transition period from the extremely low temperature to the cold state, the intake working angle 41a is gradually reduced and the intake center phase 41b is gradually retarded as the engine temperature rises.
Further, during the transition period from the cold state to the warm-up period, the intake center phase 43b is gradually advanced as the engine temperature rises. Therefore, for example, when the engine is started at a very low temperature and idle operation is continued until the warm-up is completed, while maintaining good engine startability, the intake working angle and the intake center phase are increased as the engine temperature rises. Can be smoothly changed to a characteristic that is advantageous for exhaust emission and fuel efficiency.

In the example of setting the intake center phase shown in FIG. 6 (b) described above, as shown in FIG. 3, the electric phase changing mechanism 2 is excellent in response and can set the variable amount sufficiently large.
It is suitable when 0 is used. On the other hand, FIG.
The example of setting the intake center phase shown in (c) is suitable when a hydraulically driven phase changing mechanism, which is less costly but less responsive and variable than the above-mentioned electric type, is used. Is.

The setting of FIG. 6 (c) differs from the setting of FIG. 6 (b) in that the set value 42c of the intake center phase during cold engine is set equal to the set value 44c after warming up. . The set values 40c and 44c at extremely low temperature and after warm-up are shown in FIG.
It is the same as the set values 40b and 44b in (b). Figure 6
According to the setting of (c), it is not necessary to change the intake center phase in the transition period from the cold state to the warm-up period, and the intake center phase is not changed in the transition period from the extremely low temperature to the cold state. Change amount Δ
D is very small. Therefore, compared to the setting example of FIG. 6B, it is not possible to improve the exhaust emission due to the significant retardation of the intake center phase during cold engine, but the change of the intake center phase is small. Therefore, for example, even when the engine is started from an extremely low temperature, it is possible to appropriately change the intake center phase according to the rise of the engine temperature while ensuring good engine startability.

FIG. 8 shows examples of setting the intake working angle and the intake center phase in various operating conditions. It should be noted that the values of the intake center phases P1 to P5, which will be described later, have a relationship of P1 <P2 <P3 <P4 <P5 when the advance side is positive.

First, the valve lift characteristics after warming up will be described. In the extremely low load range (a2) including idle, the intake center phase is set to a predetermined retard angle phase P2, and
The intake working angle is set to the minimum working angle, the opening timing of the intake valve is set to top dead center, and the closing timing of the intake valve is set to near bottom dead center. As a result, the residual gas is reduced, and the upper surface of the piston is not exposed to the intake negative pressure from the top dead center, and the piston is displaced to some extent to cause the negative pressure in the cylinder to open the intake valve. , The pump loss is reduced. Further, since the intake working angle is minimized, friction is reduced, gas flow is strengthened, and fuel atomization is promoted.
As a result, fuel efficiency and exhaust performance are improved. The minimum operating angle is, for example, 80 to 90 ° CA, and the retard phase P2 is a value on the retard side of at least 90 ° ATDC.

In the middle load region (c), the intake valve opening timing is set before the top dead center, mainly in order to reduce the pump loss due to the increase of the residual gas and to improve the combustion due to the high temperature residual gas. Moreover, in order to reduce the pump loss by reducing the intake air amount (filling efficiency), the intake valve closing timing is set to before the bottom dead center. Therefore, a predetermined small operating angle larger than the above minimum operating angle is set, and the intake center phase is set to the most advanced phase P.
Set to 5.

In the low load range (b) in which the intake air amount is smaller than the medium load range (c), the intake working angle is changed from the above-mentioned minimum working angle in order to mainly improve combustion and reduce residual gas. The value is set to a value between the small operating angles, and the intake center phase is set to a predetermined advance phase P4. As a result, the fuel consumption is improved by reducing the pump loss accompanying the increase in the effective compression ratio. The advance phase P4 is a value on the retard side of the maximum advance phase P5, and is a value on the advance side of 90 ° ATDC.

In the full open range (d) to (f), the intake center phase is set to a predetermined intermediate phase P3 in order to mainly improve the filling efficiency.
Alternatively, the intake working angle is increased in accordance with the increase in engine speed. For example, in the full open / low speed range (d), the intake valve opening timing (IVO) is set to approximately top dead center, and the intake valve closing timing (IVC) is set after bottom dead center.
The above-mentioned intermediate phase P3 is, for example, about 90 ° ATDC.

On the other hand, in the extremely low load region (a1) such as idling when the engine temperature is equal to or lower than a predetermined value, such as at the time of cold engine start, catalyst warm-up is insufficient, so exhaust purification by combustion improvement and In order to increase the exhaust temperature, the intake working angle is set to the minimum working angle, and the intake center phase is set to the most retarded phase P1.
The VO is retarded significantly from the top dead center. With such a setting, atomization of fuel by gas flow enhancement is promoted, and the intake valve opens after the negative pressure in the IVO has been sufficiently developed to allow the in-cylinder negative pressure to develop sufficiently. Flow is further enhanced.

Although not shown, the lift characteristics (b) in the warm-up state in the low / medium load range in the cold state,
If the same as (c), the combustion may worsen, so it is necessary to set the lift characteristics (d) in the low speed / fully open region to substantially the same setting, for example.

Unlike the setting shown in FIG. 8 (a2), the operating angle of the intake valve in the extremely low load range such as when the engine is started may be set to be smaller when the engine is cold than when it is warmed up. . In this case, the operating angle at the time of cold start is smaller than that at the time of warm-up, so the gas flow is strengthened and combustion is improved. On the other hand, at warm start, the operating angle becomes relatively larger than at cold start, and suction resistance is suppressed.
It is possible to improve fuel efficiency.

Next, with reference to FIGS. 9 to 11, the case of accelerating from each operating state will be examined. In addition, L in the figure
Reference numeral 1 represents a reference characteristic corresponding to the reference setting of the intake working angle and the intake center phase in the operating state before acceleration. Further, L2 is a target characteristic corresponding to the target operating angle and the target phase, and L3 is a characteristic in a state where only the intake operating angle is changed by a predetermined amount toward the target operating angle with respect to the reference characteristic L1. L4 represents a characteristic in which only the intake center phase is changed by a predetermined amount with respect to the reference characteristic L1 toward the target phase.

First, referring to FIG. 9, consideration will be given to acceleration from an extremely low load region (cooling idle state) during cooling. In the cold idle state, the intake center phase is set to the most retarded phase P1 as described above. Therefore, when only the intake working angle is increased in the extremely low load region, the torque may be temporarily reduced because the intake valve closing timing is excessively delayed. For example, the first rotation speed N shown in FIG.
In the rotation range lower than 1, the torque of the characteristic L3 after the operating angle is increased is lower than that of the reference characteristic L1. Therefore, if only the operating angle is changed, the torque is temporarily reduced.

On the other hand, even if only the intake center phase is advanced at the time of acceleration from such an extremely low load, the torque surely increases. Therefore, during acceleration from such an extremely low load and extremely low rotation speed range, the phase change mechanism 20 preferentially advances the intake center phase. That is, the phase changing mechanism 2
Only 0 is driven, or the amount of change in the intake center phase by the phase changing mechanism 20 is controlled to be sufficiently larger than the amount of change in the operating angle by the operating angle changing mechanism 10. As a result, the torque during the acceleration transition is reliably increased, and the torque reduction during the transition can be reliably avoided.

By the way, the reference setting (minimum operating angle and most retarded angle phase) L1 of the cold idling state is used mainly in the low rotation speed range where the rotation speed is higher than the extremely low rotation speed range, mainly for the purpose of improving combustion. To be done. However, as the engine speed increases, the intake time decreases at the same operating angle, and therefore the full-open torque cannot be effectively increased even if only the intake center phase is advanced. Therefore, in the extremely low rotation range (for example, the rotation range of the second rotation speed N2 or less where the torque is reversed between the characteristic L3 in the operating angle increasing state and the characteristic L4 in the phase advance state shown in FIG. 9), as described above. The intake center phase is preferentially advanced to a low rotation speed range (for example, the second rotation speed N
In the rotational range exceeding 2, the torque can be most efficiently increased by preferentially increasing the intake working angle.

Next, with reference to FIG. 10, a case of accelerating from an extremely low load region after warming up will be considered. In the extremely low load region after warming up, in order to mainly suppress the intake resistance and improve the fuel consumption, the post-warming retarded phase P2 that advances the intake center phase from the most retarded phase P1 as described above. Is set to. In other words, the intake valve closing timing is advanced more than when it is cold in order to mainly improve the effective compression ratio and improve combustion. Therefore, if only the intake center phase is advanced, the effective compression ratio and the charging efficiency may decrease, and the torque may not be effectively increased. Therefore, during acceleration from such an extremely low load range after warming up, the torque can be efficiently increased by preferentially increasing the intake working angle.

As described above, even when acceleration is performed from the same load range, the operating angle changing mechanism 10 is based on at least one of the engine speed and the engine temperature (cooling or warming up).
Alternatively, by preferentially driving one of the phase changing mechanisms 20, the torque can be efficiently increased, and the drivability can be improved.

Next, with reference to FIG. 11, a case where acceleration is performed from a low load region after warming up will be considered. At the time of acceleration from the low load region, as is apparent from the fact that both the characteristics L3 and L4 have higher torques than the reference characteristic L1 in FIG. 11, the torque increases even if the operating angle is increased or the phase is retarded. . However, in FIG. 11, it is clear from the fact that the characteristic L3 in the operating angle increasing state is always higher in torque than the characteristic L4 in the phase retarding state, so that the intake operating angle by the operating angle changing mechanism 10 is irrespective of the engine speed. The torque can be efficiently increased by prioritizing the increase of the torque over the retardation of the intake center phase by the phase changing mechanism 20.

Although not shown, for acceleration from a medium load range as shown in FIG. 8 (c), prioritizing an increase in the operating angle causes the IVO to become excessively fast and the intake valve and the piston to become extremely urgent. Therefore, it is preferable that the phase change mechanism 20 retard the intake central phase preferentially.

As described above, since the phase changing mechanism 20 is of the electric type, it is possible to quickly change the intake center phase regardless of the engine temperature (when the engine is cold or when it is hot). That is, the phase can be quickly changed even during cold cooling, as opposed to the hydraulic drive in which a delay in phase change is likely to occur during cold cooling. As a result, the intake valve opening timing is significantly retarded when the cold engine is started to enhance the gas flow and improve combustion.
Exhaust gas purification can be achieved. Further, after warming up, the intake center phase is slightly advanced to reduce intake resistance and improve fuel efficiency. As a result, it becomes possible to achieve a high level of both cleaning the exhaust during cooling and improving the fuel efficiency after warming up.

Further, since the operating angle changing mechanism 10 is also of an electric type, the variable width can be set to a sufficiently large value, for example, 80 to 280 ° CA, and at the time of cold start and extremely low rotation, it can be surely and quickly performed. The intake working angle can be changed. That is, by adopting such an electric operating angle changing mechanism 10, it becomes possible to drive the operating angle changing mechanism 10 preferentially even in a low speed range, for example.
Further, the operating angle can be rapidly increased regardless of the engine temperature (when the engine is cold or after warming up). Therefore, it is possible to set the minimum operating angle to a sufficiently small value as compared with the hydraulically driven configuration in which an increase in the operating angle is likely to occur when the engine is cold.
As a result, it becomes possible to effectively enhance the gas flow at the time of starting the cold machine to improve the combustion and further purify the exhaust gas.

Since both of the changing mechanisms 10 and 20 are electrically driven in this way, as described above, even when the acceleration transition period is in progress, control for switching the priority of both changing mechanisms 10 and 20 can be performed. It will be possible.

By the way, as in this embodiment, the measured value (actual center phase) of the center phase of the intake drive shaft 3 with respect to the crank angle is detected based on the detection signal from the angle detection sensor 31 of the intake drive shaft 3. In the case of the configuration, the intake center phase is detected for each rotation of the intake drive shaft 3.
On the other hand, in the case of a configuration in which the actual measurement value (actual operating angle) of the intake working angle is detected based on the detection signal from the angle detection sensor 32 of the control shaft 13, the detection interval is free and the actual operation is performed at any timing. The corner can be detected. Therefore, by detecting the actual operating angle at the timing at which the actual intake phase is detected, the target values of the intake operating angle and the intake center phase are set based on the actual intake phase and the actual operating angle detected at the same time. Control such as setting can be performed, and the control accuracy is improved.

The flow of such control will be described in detail with reference to the flowchart of FIG. In S11, when the actual intake phase is detected based on the detection signal from the angle detection sensor 31 of the intake drive shaft 3, the process proceeds to S12 and the control shaft 13
The actual operating angle is detected based on the detection signal from the angle detection sensor 32. When it is determined in the subsequent S13 that the vehicle is in the acceleration state, the process proceeds to S14, and it is determined whether the engine is in the cold state or after the warm-up based on the engine temperature and the like. When the engine is cold, the process proceeds to S16, and it is determined whether the engine speed is extremely low or low based on the engine speed. If it is in the extremely low rotation speed range, the process proceeds to S17, in which the phase changing mechanism 20 is preferentially driven. On the other hand, in the case of the low rotation speed range, the process proceeds to S18, and the operation angle changing mechanism 10 is preferentially driven.

If it is determined in S14 that the engine has been warmed up, the process proceeds to S15, in which it is determined whether the intake valve opening timing (IVO) is excessively early. If it is too fast, S1 above
7, the control is performed to preferentially drive the phase changing mechanism 20. If it is determined to be relatively slow, the process proceeds to S16, and it is determined which of the changing mechanisms 10 and 20 is to be driven preferentially according to the engine speed.

[Brief description of drawings]

FIG. 1 is a schematic perspective view showing a variable valve operating device according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a working angle changing mechanism of the variable valve operating device.

FIG. 3 is a sectional view showing a phase changing mechanism of the variable valve operating device.

FIG. 4 is a flowchart showing a flow of setting / controlling an intake working angle and an intake center phase.

FIG. 5 is a characteristic diagram showing intake valve lift characteristics with respect to engine temperature in an extremely low load range.

FIG. 6 is a characteristic diagram showing an intake working angle with respect to an engine temperature in an extremely low load region.

FIG. 7 is a characteristic diagram showing an intake working angle with respect to an engine temperature in an extremely low load range.

FIG. 8 is an explanatory view showing setting of intake valve lift characteristics in various operating states.

FIG. 9 is an explanatory diagram when accelerating from the cold idle region.

FIG. 10 is an explanatory diagram when accelerating from a warm-up idle region.

FIG. 11 is an explanatory diagram when accelerating from a warm-up low load region.

FIG. 12 is a flowchart showing a flow of setting / controlling the priority of the changing mechanism.

[Explanation of symbols]

2 ... Intake valve 3 ... Intake drive shaft 4 ... rocking cam 10 ... Operating angle changing mechanism 11 ... Drive cam 12 ... Ring-shaped link 13 ... Control axis 14 ... Control cam 15 ... Rocker Arm 16 ... Rod-shaped link 20 ... Phase change mechanism

Continued front page    F-term (reference) 3G018 AB02 AB16 BA10 BA19 BA34                       DA11 DA75 EA02 EA08 EA12                       EA13 EA17 EA21 EA22 FA01                       FA06 FA07 FA08 FA16 GA07                       GA11                 3G092 DA03 DA05 DA09 EA01 EA02                       EA03 EA04 EA08 FA24 FA25                       FA31 FA41 FA42 GA01 GA02                       GA03 GA04 GA05 GA06 GA12                       HA11Z HE02Z HE03Z HE08Z

Claims (12)

[Claims] 1. An operating angle changing mechanism capable of changing an intake operating angle of an intake valve, a phase changing mechanism capable of changing an intake center phase of the intake operating angle, and an engine temperature estimating means for estimating an engine temperature. In a variable valve operating device of an internal combustion engine having, in an extremely low load range including at least idle, an intake working angle at an extremely low temperature at which the engine temperature is lower than that at a cold time is at least larger than an intake working angle at a cold time. A variable valve operating device for an internal combustion engine, comprising: 2. The internal combustion engine according to claim 1, wherein the intake working angle is set to about 180 ° CA and the intake center phase is set to about 90 ° ATDC at the extremely low temperature in the extremely low load region. Variable valve operating system for engines. 3. The variable operation of the internal combustion engine according to claim 2, wherein, in the extremely low load region, the intake central phase during the cold engine is retarded more than the intake central phase during the extremely low temperature. Valve device. 4. The intake center phase after the warm-up is advanced from the intake center phase after the warm-up in the extremely low load region, as claimed in any one of claims 1 to 3. Variable valve device for internal combustion engine. 5. The intake working angle is set to about 90 ° CA and the intake center phase is set to about 180 ° ATDC when the engine is cold in the extremely low load region. 5. A variable valve operating device for an internal combustion engine according to item 1. 6. When the engine is accelerated, one of the operating angle changing mechanism and the phase changing mechanism is preferentially driven based on at least one of the engine speed and the engine temperature. A variable valve operating system for an internal combustion engine according to claim 1. 7. The phase changing mechanism is preferentially driven during the cold state during acceleration from an extremely low load / extremely low speed range including engine startup, and the operating angle changing mechanism is preferentially driven after warming up. The variable valve operating device for an internal combustion engine according to claim 6, wherein: 8. The phase changing mechanism is preferentially driven in the extremely low rotation speed range and the operating angle changing mechanism is preferentially driven in the low rotation speed range during acceleration from the extremely low load range in the cold state. The variable valve operating device for an internal combustion engine according to claim 6 or 7. 9. The variable valve operating system for an internal combustion engine according to claim 1, wherein at least one of the phase changing mechanism and the operating angle changing mechanism is an electric type. 10. A variable valve operating valve for an internal combustion engine according to claim 1, wherein an operating angle of the intake valve in the extremely low load region is smaller when the engine is cold than when it is warmed up. apparatus. 11. A swing cam, wherein the operating angle changing mechanism is fitted onto the intake drive shaft so as to be relatively rotatable, drives the intake valve to open and close, and a drive cam eccentrically provided on the intake drive shaft. A ring-shaped link fitted to the drive cam so as to be relatively rotatable, a control shaft arranged in parallel with the intake drive shaft,
A control cam eccentrically provided on the control shaft, a rocker arm externally fitted to the control cam so as to be relatively rotatable, and one end of which is connected to the ring-shaped link, the other end of the rocker arm and the swing cam. The variable valve operating system for an internal combustion engine according to any one of claims 1 to 10, further comprising: 12. A means for detecting a rotation angle of the intake drive shaft, a phase detection means for detecting an actual center phase of an operating angle of the intake valve based on the rotation angle of the intake drive shaft, and a rotation of the control shaft. An angle detection means and an operation angle detection means for detecting the actual operation angle of the intake valve based on the rotation angle of the control shaft are provided, and the phase detection means adjusts the actual center phase to the timing. The actual operating angle is detected by the operating angle detecting means, and the target values of the intake operating angle and the intake central phase are set based on the actual center phase and the actual operating angle. A variable valve operating device for an internal combustion engine as described above.